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This tutorial is part of our series on upgrading from Drupal 6 to 7. Click here to find other tutorials on upgrading.

Notice: unserialize() [function.unserialize]: Error at offset 74 of 75 bytes in variable_initialize() (line 749 of /srv/www//includes/bootstrap.inc).

This error and others like it often occur when updating from Drupal 6 to 7 and is caused by left-over settings from modules that did not clean up when they were uninstalled, and are not stored in the correct format. These will cause PHP errors.

A new module called Variable Check will check the database for errors and make it easy to spot the problem and delete the variable name that is causing the error message.

Step 1. Download and install Variable Check


Download the correct version from: http://drupal.org/project/variablecheck

Step 2. Install the Module


Go to Modules > Install new module and use the installation facility to install the module


Browse to find the module and install it by clicking Install.

Step 3. Activate the module.


Go to Modules and Other, and check the Enabled Box.

Step 4. Run the report


Go to Modules > Check System Variables


You will see the variables that are causing you a problem.

Step 5. Delete the variables


Check the boxes and click delete.


Confirm the delete.